The Entire 12 Monkeys Timeline Explained

From Marty McFly's grandfather paradox to the twisted family tree in the atmospheric Netflix series "Dark," time travel stories can be a ton of fun to watch –- if you can keep up with all of the wibbly-wobbly, timey-wimey plot twists, causality loops, and paradoxes, that is. In the wild and wooly world of time travel, anyone can be their own ancestor and couples can get to know each other in the wrong order, which makes creating a traditional timeline something of a challenge. But in the canon of time travel tales, one of the most brilliantly executed and rewarding to watch is Terry Matalas and Travis Fickett's "12 Monkeys."

A reimagining of Terry Gilliam's 1995 film of the same name which was itself based on the short film "La Jetée," "12 Monkeys" imagines a quest to prevent a global pandemic from wiping out most of humanity. A tale of family, redemption, and the value of a great mixtape, "12 Monkeys" follows the story of James Cole as he's enlisted to find and correct what went wrong in the past, only to learn that time travel is a much messier business than he was led to believe. To untangle some of the many loops, cycles, and Jinns, we're taking a deep dive into the complete "12 Monkeys" timeline. Initiate splinter sequence.

The mythology of "12 Monkeys" begins with the dawn of humanity. When humans begin to evolve, many develop a special connection to time. These individuals, known as Primaries, "help time think" but often suffer from hallucinations and a sense of temporal disorientation. Although the "12 Monkeys" story technically begins much later thanks to the show's wackadoo time travel mechanics, it chronologically kicks off in the year 894 when someone (Olivia Kirshner) carrying a dormant virus dies on a mountain in Nepal. Sometime during the medieval period, a group of Primaries journey to England from around the world to create a special weapon meant to repair time, which is destroyed in 1491 during a fight between two warring factions of time travelers. Throughout the ages, time travelers splinter in and out of various places and times, with a traveler named Athan even creating a life for himself in Victorian London. Time travel technology originates in the early 21st century. 

Olivia Kirschner, who will one day lead the Army of the 12 Monkeys, is genetically engineered sometime during the late 1950s by an East German eugenicist, using the genetic profile of time traveler Mantis. She spends her young childhood as a lab experiment in a bedroom-sized box ("Fatherland"). Under the guidance of her mother, she grows up practicing the Druze religion and worshiping the Witness. When the Witness commands the young Olivia to have a baby in 1971, she willingly goes out and becomes pregnant, giving her child to the Witness to raise ("45 RPM"). Throughout the ensuing decades, she barely ages and exhibits extraordinary strength and healing abilities when injured. Alongside her brother, the Pallid Man, Olivia continues to direct the Army of the 12 Monkeys as instructed under the influence of the hallucinogenic red tea.

Sometime in the late 1970s or early '80s, time travel co-author Katarina Werner is born in Dresden, Germany, unaware that her actions will one day break time. In 1995, the mysterious Army of the 12 Monkeys begins pumping funds into the biotech company Markridge, just as they will later fund Dr. Elliot Jones' temporal research. Around 2015, the U.S. government begins funding Project Spearhead, a continuity plan for the apocalypse. That same year, Katarina and Elliot fire up their splinter machine for the first time, sending the first ill-fated plant traveling through time. They marry in October 2015, but six days later Katarina tells Elliot she's pregnant and doesn't plan to stay that way. A distraught Elliot leaves her the next day, taking their work with him. At the same time, his lab assistant Emma — secretly the child of Olivia Kirschner created to learn the secrets of time travel — tells her mom she knows how to complete the large-scale splinter complex called Titan.

A woman named Dr. Cassandra Railly contacts the still-pregnant Jones, holding her at gunpoint and demanding her help saving a time traveler named James Cole. Initially resistant, Jones becomes convinced when Cassie presents her own research. Jones helps her repair Cole's blood with a small infusion from his younger self. Changed by the experience, Jones decides to keep her baby but doesn't tell Elliot. Her daughter Hannah is born in 2016 — the same year the deadly Kalavirus breaks out, killing most of the global population including scientist Dr. Adler's son. Jones and Adler take refuge with Spearhead, but Hannah later dies of an apparent Kalavirus infection, spurring Jones to finish her time travel work. 

When the virus mutates in 2033, it deals humanity another blow, killing half of those who managed to survive the first outbreak. Spearhead's leaders suggest they relocate westward where it might be safer, but the grieving Colonel Jonathan Foster instigates a bloody coup, executing anyone planning to leave and installing himself as leader. Fleeing Spearhead, Jones and several others travel to the long-abandoned Raritan facility, where she finds Elliot's splinter machine and decides to use it to stop the plague from ever happening ("Splinter"). While clearing the grounds, Jones runs into a stranger who gives her a pack of cigarettes, telling her that if one day, trading a single life for seven billion is one too many, she should save the one no matter what. As Jones and her team of scientists begin work on the machine, she attempts to recreate the injections needed to safely time travel from memory. She uses her own DNA as a template, but the first 16 test subjects die horrifically anyway. James Cole is her first successful splinter, although she never learns why until discovering the truth about his identity ("The Beginning Part 1").

While working on the splinter machine, Jones and her team continue researching the plague. Jones comes across a badly corrupted audio recording from Cassie that suggests someone named Cole can stop Leland Frost and the architects of the plague. In 2041, scavenger friends James Cole and José Ramse are captured by the Raritan security team, and Jones convinces Cole that he is the man in the recording. Cole and Ramse travel to the ruins of the CDC, where they collect information and swipe Cassie's watch from her long-dead skeleton ("Splinter").

Cole's first splinter brings him to Dr. Cassandra Railly, whom he believes can help him stop the apocalypse in a one-and-done effort. Born in 1980 Syracuse, New York, Cassie spends time in the ICU for viral meningitis as a little girl. In 1990, Cassie's mother meets with a woman named Amelia Morrison (Who's actually Cassie from the future) to share a psychological profile based on some curious writings ("Nurture"). That same year, the science-minded Cassie refuses to go to a museum with her mom — a decision she comes to regret when her mother dies unexpectedly of a pulmonary embolism. In an altered timeline, Amelia Morrison convinces Kathryn to make Cassie go to the museum, changing Future Cassie's memories ("Nurture"). Her dad puts her through Columbia University Medical School working three jobs, and she lands a job at Pennsylvania Memorial Hospital, where she is visited by a stranger who asks her for medical advice ("Cassandra Complex" and "Thief"). 

On January 4, 2013, Cassie has just finished lecturing at a Baltimore symposium on infectious disease and pandemic preparedness when she's abducted by Cole, who tells her all about herself before demanding the whereabouts of Leland Frost. Using her watch to create a paradox, he convinces her he's telling the truth. Police show up, Cole is shot, and he tells her to meet him in two years at the John Adams Hotel before disappearing in front of her eyes ("Splinter"). 

Convinced that she encountered a time traveler portending an imminent plague, Cassie becomes increasingly paranoid. When a viral outbreak hits in 2014, she travels with the CDC to Haiti to stop it, befriending a local doctor named Henri Toussaint who is later killed on a medicine run. As Cassie's paranoia about the foretold plague spirals, she's sent home from the mission, and her continued erratic behavior costs her both her relationship with political strategist Aaron Marker and her practice later that same year ("Cassandra Complex"). 

Cassie shows up at the hotel in 2015 as Cole instructed. He arrives still bleeding from the gunshot she saw him get two years before. After patching him up, she and Cole pump her dad's NSA buddy for dirt on Frost, whose real name is Leland Goines. They crash a party to meet Goines, who recognizes Cole from a past encounter Cole hasn't had yet, abducting him and Cassie to Markridge. Cole uses another paradox to break free, killing Goines on his way out. Surprised he hasn't been erased, Cole heads home to regroup. 

Cassie finds her friend Jeremy dead, his body covered in jasmine and lavender petals, and is confronted by the Pallid Man, who warns her to stop asking questions and inquires about Cole ("Mentally Divergent"). Cassie's ex Aaron uses his connections to learn there's a cover-up surrounding Goines' death. This intel leads Cassie to the J.D. Peoples Mental Hospital, where Cole got himself admitted to question Goines' institutionalized daughter Jennifer, who's accused of killing her Markridge colleagues in the lab where the virus was kept. Cassie poses as Cole's doctor to get him released, and they watch as the Pallid Man abducts Jennifer on their way out. When police question Cassie about what she saw, she recognizes Henri Toussaint in a photo of Jennifer's co-workers. Cole splinters to Haiti 2014, where he learns more about the Night Room but is forced to kill Toussaint to prevent the Monkeys from getting his information ("Cassandra Complex"). 

Cole is in 2015 with Cassie when Jones brings him back early to help fight off the West VII, a gang of scavengers he once belonged to. When they lose the facility and Ramse is killed, Jones sends Cole back to 2015 but misses, only sending him back two days where he is captured by the West VII and inadvertently gives them a way into the facility. He escapes with a little help just in time to save the day, closing the time loop and showing the audience how time loops work at the same time ("Atari").

Back in 2015, Cassie starts working for the CDC. She and Cole locate the Night Room, where they run into the Pallid Man, Olivia, and Jennifer. They manage to burn the origin of the virus, but Cassie gets killed the first time around, forcing Cole to loop through a second time with Aaron as backup. Before they can rescue Cassie, the Monkeys feed her red tea, yielding haunting visions of the Red Forest, a house of cedar and pine, and the plague doctor mask-wearing enigma called the Witness.

Cole and Cassie begin looking into the 12 Monkeys while the U.S. government makes plans to weaponize Markridge's virus, which was extracted from the Origin before the Big Burn. They plan to release it in Chechnya to stop info leaker Adam Wexler. Cassie and Cole crash a museum party, where they share a dance and learn the Monkeys are linked to the Druze religion in Chechnya ("The Keys"). Cassie later receives a call from Future Cole, who has traveled back one week to investigate Operation Troy in Chechnya, where he has learned the virus first gets released. Aaron helps her contact the CIA and Markridge, and they convince the government to bomb the site, which will kill Cole but hopefully erase him from the timeline. After the bombing, Cassie visits the bomb site and finds no sign of Cole, leading her to believe the virus has been stopped for good. In reality, Cole splintered two years into the pandemic-ravaged future because the splinter machine's power core is failing. Stuck there with no way home, he goes to find Future Cassie at the CDC, where she gives him an address moments before he watches her die ("Tomorrow").

While Cole is still in 2017, Jones sends Ramse and others to Project Spearhead for their power core, and Ramse runs into his old flame Elena, who introduces him to his son Sam. When Spearhead's leader won't give up the core, Jones' people take it by force, bringing Cole back. When Past Cole arrives in 2015 to ask about Operation Troy, Aaron and Cassie play along knowing that any deviation could alter the timeline. They rekindle their romance, but just as they are moving on with their lives, Cole comes back again to tell them their plan didn't work.

Cassie and a demoralized Cole track down Markridge scientist Oliver Peters, who says the Monkeys forced him to create the virus again by threatening to kill his husband. A frustrated Aaron suggests they just accept the situation and plan for their survival with Project Spearhead, leading to tension between him and Cassie. Things are no better in 2043 between Cole and Ramse, who's convinced that undoing the pandemic will erase his son. Ramse steals the injections, burning the research room for good measure as he leaves. Outside of Raritan, among the Spearhead refugees, Ramse spies the Daughters, a band of tough post-apocalyptic women led by Future Jennifer Goines. Old Jennifer tells him they need to defeat the Witness and gives him a pendant with the Titan symbol on it. In the effort to get the injections back, Elena is killed, causing Ramse to snap. He sets out to bomb the splinter machine but ends up trapped. After shooting a few Project Splinter teammates, he injects himself and hops into the machine, which is primed for Cole's visit to 1987 Japan ("Divine Move"). 

Cole's body is failing, and Jones tells him to use his final jump to visit 1987 Japan and stop Ramse. They find themselves in a Yakuza den Leland Goines and the Origin. Cole inadvertently tells Goines about the virus, leading to Goines' procurement of it. When the fight continues and Ramse stabs Cole, Jones sends him to Cassie in 2015, while Ramse, left stranded in 1987, spends the next eight years behind bars in Shonin prison. After his release, Olivia brings him into the Army of the 12 Monkeys, where he spends the next couple of decades filling them in on every detail of Cole's plan before it can happen ("Shonin"). 

With Cole dying in 2015 and his tether gone, Cassie locates 2015 Katarina Jones in Manhattan, convincing her to help with Cole by sharing Jones' future research. They find Kid Cole and convince his dad to help out by using Kid Cole's blood to somehow repair 2043 Cole. Before they can, Aaron shows up, begging Cassie to go with him to Spearhead. The Monkeys show up, and Cole's dad dies protecting his present and future son. As they attack, Cole injects the blood, creating a paradox that sends the Monkeys and the Pallid Man flying ("Paradox"). 

Cassie, Cole, and Jones drop the newly-orphaned Kid Cole off at a children's home, where he meets Kid Ramse for the first time. Jones decides to keep her baby while a healed Cole gets used to life with Cassie in 2015. Cole tracks down Aaron, who reveals under interrogation the Monkeys' plans for Spearhead and the virus but is burned alive while attempting to flee. Cassie and Cole visit Markridge's new CEO, Jennifer Goines, and end up in a stand-off at Raritan with Ramse, who's planning to splinter back to 2043. Ramse and Cassie are both shot in the melee, and Ramse sacrifices his injections to send Cassie back to Jones in the future ("Arms of Mine").

After a painful splinter, Cassie arrives in 2043 to a surprised Jones amid Raritan's occupation by Deacon and Olivia's bioengineered 12 Messengers. While Jones patches Cassie up, the Messengers attempt to use the splinter machine. Cassie convinces Deacon to turn on them, promising to treat his Wilson's disease, and Deacon's crew, the West VII, help take the facility back after only a few Messengers splinter. Deacon and his crew stay on at Raritan, where he trains Cassie to fight and scavenge for eight months while Jones and her team work on repairing the splinter machine ("Primary"). He and Cassie briefly hook up while out on a difficult run, and for Deacon, there are feelings involved.

By 2044, Team Splinter tracks the virus to Jennifer's release in New York City, and a now-hardened Cassie splinters in to stop her. Cole talks Jennifer into giving up the virus sample, and Cassie and Cole work together to burn the remaining virus, which is stashed in a plane's cargo hold waiting for Jennifer to deliver it around the world. As the virus burns, they can feel time changing around them just as Jones can in the future. In this new timeline, the plague begins in 2018 rather than 2016, and a higher level of CDC preparedness leads to hundreds of thousands of lives saved, but the world is still dying from Kalavirus mutations ("Year of the Monkey"). 

When Cole refuses to kill Jennifer, Cassie uses his tether on Ramse instead, sending him back to 2044 with her to be interrogated. At Old Jennifer's insistence, Cassie later brings Cole back from 2016, reluctantly agreeing to work together. Amid a dramatic increase in temporal anomalies, Cole and Cassie travel to a 1944 Columbia University event from a picture of themselves, where they realize a pair of Messengers attempted to kill a Primary, erroneously killing his father instead. Cassie and Cole rush to save their intended target, Tommy Crawford, at Mission Cross Mental Asylum. Cassie kills one Messenger, but his partner Mantis paradoxes Tommy, creating the very beginning of the Red Forest and cutting off Cassie and Cole's tethers to 2043 ("One Hundred Years").

In exchange for his freedom, Jones sends Ramse to two days earlier in 1944, but he's immediately hit by a car, landing him in a hospital. He breaks out, reaching the mental asylum just before the paradox but failing to stop it. Ramse watches as FBI Agent Robert Gale arrests and detains Cassie and Cole, following them to free them. Cole goes after the Messenger, who tells him of her mission to stop time and bring about the Red Forest. He also bumps into Gale, who's figured out the truth about the time travelers. Ramse places an ad in the paper so that Jones can find them and bring them back to 2044 ("Emergence").

When the 2044 skies begin turning red, Cole asks Future Jennifer and the Daughters to seek shelter at Project Splinter. She declines, telling Cole he needs to find a Primary to help him ("Primary"). Since 2044 Jennifer's powers have faded, she sends a reluctant Cassie back to the past to find her and help track down the next Primary. Cassie finds her at the Emerson Hotel where Team Splinter has a permanent residence, taking the unhelpfully clear-headed Jennifer Goines to her family summer house to trigger a vision since her meds are suppressing them. Jennifer's childhood trauma rekindles her visions, and seeing just how much pain Jennifer is in inspires Cassie to treat her more kindly.

As Cassie looks for clues hidden in Jennifer's old bedroom, the Monkeys show up, abducting Cassie and Jennifer to Monkey Manor. There, Jennifer sees the Word of the Witness –- an expansive map of time complete with crucial information including her own death date. Olivia sends Cassie on another red tea trip, but Jennifer frees her, pushing Olivia into a drained pool where she is left paralyzed. Cassie remains in 2016 to look after Jennifer, sending Cole back to the future with the information she found on the next Primary. But long after Cassie sobers up, she continues to see a vision of Aaron in her mind — a vision she comes to realize is actually the Witness trying to make the Red Forest look appealing ("Immortal"). Shaken by the visions, she tells Jennifer they need to split up. Meanwhile, Cole and Ramse travel from 2044 to the 1970s, where their successful efforts to stop another Primary paradox take them into the den of a serial killer ("Immortal").

Cassie returns to 2044, still seeing the Witness and believing she saw another traveler in the time stream. Possessing Cassie, the Witness sabotages the Splinter machine, which begins to melt down, dispersing the temporal stream and radiation throughout the facility and splintering people and things into and out of the facility ("Meltdown"). They get the facility back, exorcizing the Witness from Cassie with a little Splinter magic and her feelings for Cole, but Ramse's son is splintered away in the process with no tether.

Racked with guilt, Jones hatches a plot to send Cassie to kill her in 2020, since all of the time travel problems begin with her creation of the splinter machine. Cassie travels to 2020 Spearhead in the middle of the pandemic, killing Jones as she holds her dead daughter's hand, but it sends her into a time loop, kicking her back to that morning every time she attempts it ("Lullaby"). In 2044, Jones realizes there's a problem and sends Cole back to Cassie, where they encounter Jennifer in Spearhead's detention facility. Repeating the time loop again and again, they conclude that time keeps resetting because the creator of time travel can't die. Cassie also realizes that Hannah has very treatable meningitis. They save her, but because Hannah's death is necessary for time travel to work, they give her to Jennifer to raise, allowing Jones to believe she died. The time loop ends, and they travel back to 2044, finally revealing the truth to Jones, who tearfully reunites with her now-grown daughter.

While Cole travels back to help Jennifer and her Hyena gang find Oliver Peters, Cassie and Ramse look for the Titan from her Witness-induced vision, believing Ramse's son Sam is being held there. In 2044, Cassie and Ramse visit the Keeper and get information leading them to 1961 Berlin, while in 2016, Cole and Jennifer use Peters as bait to kidnap the Pallid Man and get intel on a Primary in 1957 ("Hyena").

With the team at odds over which of the two tips to follow and the Splinter facility imminently threatened by red temporal storms, Cassie, Ramse, and Adler deceive the others, sending the travelers to 1961 instead of '57. They drug Cole before he can figure out what they've done. A desperate Cole rings up his FBI pal Gale, who travels with him to East Berlin ("Fatherland"). Cassie and Ramse find Dr. Kirschner and get tangled up with Massad, inadvertently giving Kirschner the clue they were there to track down in the process by mentioning Titan and the Witness. 

The trip proves fruitful anyway, as they learn Kirschner is the eugenics mastermind behind the Messenger DNA, but Gale is shot at the Berlin Wall. At Kirschner's lab, they see the Word of the Witness and the bioengineered child of Mantis but splinter away before they can stop him. Ramse rips the location of Titan from the Word of the Witness as he splinters. Arriving back in 2044, Cole has Ramse and Cassie arrested for their deception.

As the temporal storms descend on Raritan with time for only one jump, Cassie, Ramse, and Adler hatch a coup to take the facility and find Titan in Colorado. As the two factions grapple for control, Cole recruits Deacon and the Daughters to retake the facility. Realizing it's her scheduled death date, 2044 Jennifer allows herself to be shot, convincing Cole to bring 2016 Jennifer to lead the Daughters. After meeting her future self, Jennifer convinces the Daughters to back down, and peace is brokered between the two groups. Jennifer leads the Daughters and Ramse to Titan by land. Meanwhile, Cole heads to 1957 to stop a time-ending paradox and prevent the facility's destruction in the present. Cassie changes her mind at the last moment, joining Cole in 1957 ("12 Monkeys").

With 11 months to find the Primary, Cassie and Cole become accustomed to life in 1957, getting jobs at the facility where the paradox will occur. When they finally locate the Primary, they learn she's dying of cancer and married to her Messenger. Like Tommy, she willingly sacrifices herself to be with her husband in the Red Forest. Failing to stop the paradox, Cassie and Cole find themselves trapped in 1957, and Cole unwittingly buys the house of cedar and pine from Cassie's visions. With no more missions and no hope to stop the Red Forest, they decide to take what time they have together, living happily for two years there and celebrating Christmas with a pregnancy ultrasound ("Blood Washed Away"). But when Cole meets a Primary in 1959 who convinces him to undo their relationship to save time, he uses the red tea to send his consciousness through time and stop the paradox, erasing their time together ("Memory of Tomorrow"). 

Cassie and Cole arrive in 2044, where Jones has watched time collapse and rebuild itself for a year. From his red tea trip, Cole foresaw a catastrophe at Titan. Cassie, Cole, and Jones splinter through space and stop this. Upon arriving near Titan, they locate Jennifer, who rallies the Daughters with her own sacrifice. They arrive just in time to save their people, but instead of leaving, they decide to search the grounds. Cassie remembers her home with Cole and the two years he erased, while Jones realizes that Titan is one giant machine. Everyone tries to escape as the city splinters, sending Jennifer to 1917 war-torn France, where she spends the next few years. Cole watches the city splinter away with Cassie and Deacon ("Guardians"). Upon arriving back at Raritan, Jones and Cole learn that Titan has splintered to somewhere in 2163, and Cassie's tether is now lost to them. 

In 2163, Cassie is brought before a congregation of Monkey acolytes, where the Pallid Man tells her she is the mother of the Witness ("Mother"). As Cole and Jones spend months searching for her, the Monkeys hold her under guard, thwarting her many efforts to escape ("Enemy"). When Cassie gives birth, they immediately steal her child, hiding him throughout space and time under the watch of the Four Horseman ("Guardians"). Unaware of the pregnancy, Deacon escapes and frees Cassie. 

They travel to the ruins of Raritan using trackers buried by Cole, where only he and Cassie know the truth about their son, Athan. Meanwhile, Ramse is with the 12 Monkeys, where Olivia reveals she has his grown son Sam moments before Sam dies. 2044 Olivia convinces him to turn her in to Jones ("Guardians" and "Enemy"). Ramse and Cole splinter to 2007, where Ramse plans to sneak off and kill Cassie, but Cole gets wise to his plan and kills him in the snow ("Brothers").

On a tip from the caged Olivia, Cassie, Cole, Jennifer, and Deacon travel to 1989 to pull off a heist and nab the Word of the Witness ("Causality"). Posing as her mother, Jennifer crashes an auction where the Word is being hidden in a painting. Meanwhile, Cole and Cassie sneak into the warehouse where it's being held to steal it. Despite a few kinks in their plan, Jennifer manages to Xerox the Word, but in doing so learns about Cassie and Cole's secret, covering the detail with her hand on the copier. Arriving back at Raritan, they bury the trackers that will bring Cassie and Ramse back from Titan to ensure the causality loop is completed.

Cassie and Cole travel to the Emerson Hotel around Christmas 1953. Using the Word of the Witness, they meet up with Gale and ask him to help them stop the First Gathering of the Faithful in a mining town called Hope Valley, annotated on the Word as the "winter of ash and blood." There, they learn that a minister is recruiting grieving locals to his secretive cult, and Cassie convinces him to invite her to a "wake" for the miners who recently died. Cole tells Gale he dies helping them in Berlin. Gale waits outside the revival tent as Cassie and Cole go inside, where they see the missionary's wife Mantis, their son, and another boy on stage. The missionary introduces the Witness, who Cole and Cassie realize is their son. Magdelena forces Athan to choose one attendee to survive and then release toxic gas inside of the tent, but Gale sees what's happening and helps his friends escape. While drawing the survivor, young Athan gives Jennifer a vision and draws a message for Gale as well. On their way out, Cole gets his hands on a splinter suit from one of the Monkeys, which Jones then reverse-engineers.

Knowing the young Witness's location, the Raritan team faces the reality of having to kill a child to save billions of lives. Meanwhile, Deacon and Jones suspect something is up with Cassie and Cole. Cole, Deacon, Whitley, Hannah, and Jennifer travel back to Christmas 1953, this time heading to Raritan. Cassie, who can't bear the thought of killing her own son, stays out of it, instead traveling to 1990 to see her mother before she dies ("Nurture"). While Cassie is gone, the suspicious Jones travels to the moment of Ramse's death, where she learns about Cassie and Cole's secret — a fact she wastes no time confronting Cassie about upon her return. But before Jones can jail her, Cassie swipes a splinter suit and uses it to splinter to 1953. While Cassie kills Magdelena, Cole gets his chance to shoot Athan but can't bring himself to. Cassie shoots Deacon to keep him from killing her son and Hannah is stabbed in the battle. As Jennifer, Whitley, Deacon, and Hannah splinter back home, Athan's tutor takes him away. Cassie and Cole, who now have splinter suits, leave together to search for him.

They travel to Athan's home in Victorian-era London, where they learn his life story from his diaries. They realize Athan had come to see Cassie years ago. Using his tale of heartbreak and loss, they catch up with their grown son at his lost love's wake and find him an angry and bitter man ready to return to his destiny and end time. Using the suits, they chase Athan through the 18th century and the London Blitz, where Athan destroys Cassie's suit. They catch up with him in the modern era and drag him back to 1959 and the house of cedar and pine.

Jones lets Olivia use red tea to find Athan and learn where the travelers have gone, but after she and Deacon leave, Olivia and her crew take over the facility. They travel to Titan, where Olivia kills her brother ("Witness"). As Athan and his parents talk through their issues, the Monkeys and Team Splinter converge on the house of cedar and pine. Jones shoots Athan's suit, causing him to splinter away. Believing Athan is dead, the Monkeys burn down the house and bring Cassie, Cole, and Jones into Titan, where they find Olivia and realize she has led them to this very moment. Jones is stabbed, and a hooded figure splinters into Titan, opening fire on the Monkeys before revealing himself to be Athan. He reconciles with his dad and helps his parents escape but is captured and brought to Olivia. There, he delivers a message: She is the Witness, not him. As payment for this information, she slashes his throat, thus fulfilling his prophecy ("Witness").

With Hannah's help, Cassie saves the badly injured Jones. Before they can think of a plan, Olivia splinters Titan to Raritan to kill all of them and stop them from ruining her plans for the Red Forest. The near-dying Jones has a secret weapon up her sleeve: Project Charon, which turns the entire facility into a machine like Titan ("The End"). As the Monkeys invade Raritan, Deacon sabotages Titan to buy them some time, while Jones intentionally exposes herself to splinter radiation to cool the core. At the end of the battle, Whitley and Laskey are killed, Deacon is left behind, and Raritan has splintered to the Emerson. Back in 2018, Jennifer tracks down the Ouroboros puzzle artifact at a Prague museum. Cole splinters in and saves her when she is cornered by authorities ("Ouroboros").

Team Splinter realizes they've not only traveled in space but time as well, splintering into the year when Cole made his first journey. Since their machine is currently inoperable, they travel to this time's Raritan. Jones visits her past self and gives herself the answer to the splinter machine, a moment she would later attribute to drunken hallucinations. With her other self sufficiently passed out, she poses as herself to gain access to the splinter machine. Cassie heads to 1971 to find and kill Olivia, while Cole and Jones jack some energy from the original machine before watching Cole's first splinter once more ("Ouroboros").

When Cassie finds Olivia, she finds a pregnant teenage runaway being forced by her mother and the Witness to have a child. She travels to Monkey Manor to stop Mantis but learns the Messenger has lost faith in the Witness. The zealous Teen Olivia will do anything to ensure the child is born. Possessed by the Witness, Olivia tells Cassie she killed Athan. Cassie tries to shoot her, but Mantis protects the girl, getting shot in the process. Cassie returns to the Emerson where Cole is waiting to take her home.

Team Splinter travels to the Old West, specifically May 1852 Blackleaf, Montana ("Legacy"). They find themselves in a town filled with anachronisms, and after running into Elliot Jones and the Pallid Man at an earlier point in his timeline, they learn this is where Titan is created. Hannah brings Elliot to Jones in the future, and they tell him what becomes of his work, causing him to realize Titan can create a paradox big enough to produce the Red Forest. Jennifer admits she's no longer Primary, but a Primary Siksika Nation man shows up, telling them the Seers made them a weapon. Jennifer drinks the red tea, leading Olivia to the Seers and themselves. Elliot and Hannah return to Blackleaf, where Team Splinter tries to take out Titan Tower. Elliot gives Hannah his Titan flash drive moments before getting killed by Deacon. Back at Team Splinter, Jones admits she's dying soon and asks them to work together as a family.

Team Splinter follows a clue to 1966, where they hope to find the secret Primary weapon ("After"). Instead, they find a couple of dead bodies and a briefcase full of money that leads them into a very messy time loop in which Cole dies and Cassie travels back earlier to save him. The Missionary tells Cassie he dreams of reuniting with his lost love in the Red Forest, killing Cole to prove his point. Cassie travels back to Splinter HQ again, where they realize Gale survived Berlin with a bulletproof vest, leaving clues in his FBI files. Fearing a paradox if Cassie returns again, Jennifer travels to the Emerson to find him. With the FBI's help, they go to the motel where Cassie and Cole find the clue written on the wall. They end up creating their own clue yet again in an "oops loop." Gale kills the Missionary and the young Pallid Man runs away while Jennifer helps Cassie save Cole. When Jennifer sees Deacon taking the weapon for Olivia, he tells her he's exactly where he wants to be.

At Gale's recommendation, Jones and the others travel to World War II France to get the weapon known as Die Glocke from the Ahnenerbe, infiltrating a gala where it's being displayed ("Die Glocke"). They become entangled in a French resistance bomb plot and run into Deacon, who tells Cole he's been working for Olivia as a double agent. Jennifer performs Pink's "U + Ur Hand" for Hitler, while Cole, Deacon, and a BDSM-clad Cassie kill a bunch of Nazis and make off with Die Glocke, an ancient, monkey-shaped bell, ensuring the "weapon" Deacon gets in 1966 is the wrong one. 

Accepting the inevitability of her own death, Jones allows Deacon to bring her to Olivia ("Daughters"). Olivia picks through Jones' head, but Jones turns the tables on her, looking into her mind as well. She tricks her into splintering Titan to 1491 –- the date on the Glocke -– where Team Splinter can use it as a beacon to splinter in, with no guarantee they can return again. They send Jennifer first, but before Cassie and Cole can splinter, 2043 Jennifer shows up to advise them.

Alone in 1491, Jennifer is immediately taken for a medieval witch and thrown in a cage ("Demons"). Moments before Cassie and Cole arrive guns blazing, a bright young Seer named Chorus frees her, taking them to her inventor dad Nicodemus' castle where Deacon is waiting. Deacon gives Jennifer his knife, telling her he will want it back someday. Olivia uses a bad Primary to find the other Seers and burn them alive. Team Splinter travels to a clifftop cathedral where the Bell begins to hum, turning on the weapon.

There, they find the original Bell, which Jennifer uses to make a paradox and turn on the machine. But before Cole can step into the stream, Olivia's primary turns it off. As a distraught Cole, Cassie, and Jennifer watch, Olivia has Deacon beheaded, turning to Cole next. Just as he's about to be killed, a splinter suit appears in front of him, and he uses it to leave and grab the women. Before he can save Deacon, Olivia uses Titan to destroy the weapon, making it impossible to return to that timeline, meaning Deacon is gone for good ("Demons").

As Olivia's daughter Emma grows closer to completing the Titan's paradox capabilities, she grows tired of her abusive mother and travels back to 2009 to live her own life. She takes the name Marion Woods, which happens to be Cole's mother's name. Hannah travels there to find her, and the two end up on the run together from the Monkeys, who destroy Hannah's injection in the fight. Emma tells Hannah the truth about who she is, and Hannah tells Emma that she will become James Cole's mother. They decide to find Katarina and Elliot, but on the way the Monkeys find them, shooting Emma and crashing their truck. Hannah runs into the woods for help, where Matthew Cole finds them. When Emma dies, Matthew mistakes Hannah's name for Marion. She stays on to protect him, and they fall in love. Hannah becomes pregnant with his child, but knowing Cole's future, she leaves, returning only to leave Cole in his care, warn him about the Army of the 12 Monkeys, and provide the Ouroboros story Cole's dad will read him as a child.

Jones continues to work on the Primary code, now too weak to stand. When she simulates the Primary code against the current timestream, all of the causality loops untangle. She and Dr. Ecklund conclude the dates don't represent splintering, but every time Cole has affected the time stream. In other words, the Primary machine's purpose was to erase James Cole, which means Cole's mother must have been a time traveler –- specifically, Hannah ("One Minute More").

Back at Project Splinter, a distraught Jennifer pours out all of the visions in her mind in yellow chalk. Jones and Adler work on deciphering the symbols, realizing they're a temporal code filled with date coordinates for everywhen they have been. Only one set of coordinates stands out as one they haven't been to: JFK airport on April 3, 2018 –- two days before the plague is released. When Cassie, Cole, and Hannah splinter to the coordinates, they find the airport in chaos with a broken vial on the ground and the Pallid Man walking away. Back in 2043, Jones concludes that the vial was the only surviving sample of M5-10, the precursor to the Kalavirus. They travel back earlier to Markridge and obtain the vial before it can be released.

When Cassie and Cole arrive at the Emerson, they find Hannah waiting for them after being stranded nine years. She tells them about Olivia's plans, explaining that because Olivia will exist outside of time once she fires up Titan, destroying the plague would cost them access to time travel, robbing them of the only chance they have at stopping her. This leads Cole to a shocking revelation –- the Primaries didn't send Team Splinter to destroy the plague, but to ensure its release ("One Minute More"). Reaching from Titan, Olivia contacts 2018 Pallid Man as the Witness, telling him to end James Cole's cycle and ensure the plague is released.

Back at JFK, the Witness shoots Cole but Hannah fatally takes the bullet for him, telling him she chose to protect him one last time. She remembers the words of the Missionary just as the Pallid Man shows up, reminding her how cruel time is. Cassie breaks the vial, releasing the virus that will spread around the world within the next two days. Back at the Future Emerson, Cole finds a letter from Hannah containing her story. Cole and Jones return to Hannah's timeline before she makes the final sacrifice, telling her everything, and they share their only tender moment together as a family knowing it's one of Hannah's last ("The Beginning Part I"). Team Splinter returns home as the red storms continue to spread throughout time. There, they're forced to grapple with the truth: Cole is the demon gumming up the works of time, and to save all of time, he must be erased.

As Titan computes its final sequence, Olivia prepares her people to usher in the Red Forest. With Jones nearing her final hours, a demoralized Team Splinter realizes they have to sacrifice Cole, but first they must complete their cycles, still unsure of how to erase him before time collapses. Cole travels back in time to when he spoke with himself at the abandoned Emerson, delivering the speech he's already heard to prepare himself for everything he has to do. He then splinters to 2018 Prague, where he saves Jennifer when she falls from the train platform, telling her he's the last Cole he's ever going to be ("The Beginning Part I").

With only 12 hours remaining and time storms raging around them, they realize they don't have enough processing power to figure out the method for erasing Cole. Cassie pleads with him to just go hide somewhere in time, but he knows it's not what's meant to be. Cole hatches a plan to take Titan, but they need everyone on board –- even their lost friends. Cole goes to the moment before Ramse's death and grabs him. In 2043, he hugs his crying friend and then tells him the whole story, including the fact that Ramse still has to die. While fixing up his dad's classic Camaro, Cole finds Hannah's ring, which he gives to Cassie after splintering them both to the Florida Keys.

Jennifer drinks the Red Tea to get into Olivia's head and lure Titan to 2043 so Team Splinter can jack into their tech, while Ramse and Cole drive straight into Titan. The Monkeys open fire, but Ramse and Cole plant a bomb in the car and splinter out in the nick of time. Using Project Charon, Jones fires up the Raritan facility, shooting temporal energy into Titan so it can't splinter away. With the Daughters' help, Team Splinter sets out to take Titan while Olivia initiates the final sequence ("The Beginning Part 1").

As Jennifer gets the Primary code into Titan's computer, the Monkeys take over Raritan. Just as the tide of battle has turned against Team Splinter, 2043 Jennifer arrives with reinforcements, having recruited Deacon and the West VII by telling him the whole story. With only moments left until the Red Forest arrives, Cassie and Jennifer find Olivia and get into post-apocalyptic fisticuffs. Olivia is thrown into the time stream, her mutilated torso dying in the 894 Himalayas and becoming the Origin. With one minute remaining, Cassie can't bring herself to stop the timer, and the Red Forest begins to destroy everything. Cole arrives, telling her, "We can have forever, or we can have now with an ending -– one that makes it real. Please, give us an ending." Moved by his words, she stops the timer, causing the Red Forest to disappear ("The Beginning Part 2").

Team Splinter sets about completing their cycles to preserve causality, returning to their timelines of origin. Cassie says goodbye to Deacon, who hasn't met her yet in his timeline. As he leaves, Old Jennifer tells him she'll coach him through his future, with Deacon remarking, "It's gonna be a hell of a performance." Ramse and Cole say goodbye, and Cole returns Ramse to the moment of his death. Jones thanks Jennifer for raising her daughter, which she hasn't yet done, and Jennifer splinters away, realizing her story is just beginning.

Cole returns Cassie's watch, which she's wearing when he finds her corpse at the CDC, and Cassie returns to become the voice of the Maryland CDC after a passionate goodbye. She leaves her final message for Cole that began the mission, telling him to remember that death can be undone, but love cannot, before dying at the CDC. Jones finishes processing the code with Titan's system, sharing a final moment with her grandson before he splinters away to be erased. After watching her die, he steps into the splinter machine one last time, erasing himself from the timeline and resetting time.

Unlike the ending of the "12 Monkeys" film, the Syfy series gets a happy ending once the pandemic and time travel are erased. In 2013 Baltimore, Cassie gets an uneasy feeling after giving her lecture on pandemics, telling Aaron she feels like there's something she forgot to do. As she sits down in her car, her memories of the other timeline begin returning, and she looks at her watch in distress. She travels to the Emerson Hotel, but they have no memory of Room 607 or James Cole. She returns to her life, sadly recalling "the family I love but never knew." A doctor once more, Cassie buys the house of cedar and pine and begins fixing it up, grateful for the opportunity to save one life at a time but lonely for the person she knew who never existed. 

Jennifer becomes the CEO of Markridge, where she bioengineers a unicorn, and Dr. Laskey and Ecklund become friends, playing chess in the park together. Katarina and Elliot end up living happily together, raising their daughter Hannah as a family. And in the future, Ramse will raise his son, Sam, while Deacon and his brother end up running a bar together where Old Jennifer is a regular. Instead of disappearing forever, Cole washes up in the Florida Keys, where he's greeted by a cheerful Jennifer. Inspired by Athan's words, Jones programmed the machine to delete him from the timeline but spit him out in the Keys. He travels to the house of cedar and pine, where he reunites with Cassie to live out their lives together for "happily ever now."